General Overview


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This report is the result of the use of the python package bgc_md, as means to translate published models to a common language. The underlying yaml file was created by Verónika Ceballos-Núñez (Orcid ID: 0000-0002-0046-1160) on .

About the model

The model depicted in this document considers carbon allocation with a process based approach. It was originally described by Trugman et al. (2018).

state_variables
Name Description Unit
\(C\) Non-structural carbon (NSC), starch \(kgC\cdot m^{-2}\)
\(X\) Xylem biomass \(kgC\cdot m^{-2}\)
\(L\) Leaf and fine roots biomass which are linearly related through a constant \(kgC\cdot m^{-2}\)
photosynthetic_parameters
Name Description Unit
\(t\) time step \(month\)
\(A_{n}\) whole-plant net photosynthesis (classic photosynthetic model of CO2 demand for carbon-limited photosynthesis), function of the interstitial CO2 concentration, the daytime leaf respiration, the maximum rate of carboxylation, and empirical constants -
cycling_rates
Name Description Expression
\(C_{i}\) initial NSC that covers carbon for two crown and fine root flushes -
\(W_{max}\) Maximum m sucrose loading rate and depends on tree size. -
\(k_{c}\) Michaelis constant for the sucrose loading rate -
\(W\) Sucrose loading rate from storage to the phloem \(W=\frac{C\cdot W_{max}}{C + C_{i}\cdot k_{c}}\)
\(L_{opt}\) Optimal total leaf biomass -
\(U\) Variable optimized in the system in the range [0,1]. Fraction of translocatable C invested in xylem reconstruction \(U=\frac{X\cdot\left(- L_{opt}\cdot\left(m_{L} + m_{X}\right) + W\right)}{W\cdot\left(L_{opt} + X\right)}\)
release_rates
Name Description Unit
\(m_{X}\) Turnover rate of the xylem \(month^{-1}\)
\(m_{L}\) Turnover rate of the xylem \(month^{-1}\)
components
Name Description Expression
\(x\) vector of states for vegetation \(x=\left[\begin{matrix}C\\X\\L\end{matrix}\right]\)
\(u\) scalar function of photosynthetic inputs \(u=A_{n}\)
\(\beta\) vector of partitioning coefficients of photosynthetically fixed carbon \(\beta=\left[\begin{matrix}1\\0\\0\end{matrix}\right]\)
\(B\) matrix of cycling rates \(B=\left[\begin{matrix}-\frac{W}{C} & 0 & 0\\\frac{U\cdot W}{C} & - m_{X} & 0\\\frac{W\cdot\left(1 - U\right)}{C} & 0 & - m_{L}\end{matrix}\right]\)
\(f_{v}\) the righthandside of the ode \(f_{v}=u\beta + B x\)

Pool model representation


Figure 1
Figure 1: Pool model representation

Input fluxes

\(C: A_{n}\)

Output fluxes

\(X: X\cdot m_{X}\)
\(L: L\cdot m_{L}\)

Internal fluxes

\(C \rightarrow X: \frac{X\cdot\left(C\cdot W_{max} - L_{opt}\cdot\left(C + C_{i}\cdot k_{c}\right)\cdot\left(m_{L} + m_{X}\right)\right)}{\left(C + C_{i}\cdot k_{c}\right)\cdot\left(L_{opt} + X\right)}\)
\(C \rightarrow L: \frac{C\cdot W_{max}\cdot\left(L_{opt} + X\right) - X\cdot\left(C\cdot W_{max} - L_{opt}\cdot\left(C + C_{i}\cdot k_{c}\right)\cdot\left(m_{L} + m_{X}\right)\right)}{\left(C + C_{i}\cdot k_{c}\right)\cdot\left(L_{opt} + X\right)}\)

Steady state formulas

\(C = -\frac{A_{n}\cdot C_{i}\cdot k_{c}}{A_{n} - W_{max}}\)

\(X = 0\)

\(L = \frac{A_{n}}{m_{L}}\)

\(C = -\frac{A_{n}\cdot C_{i}\cdot k_{c}}{A_{n} - W_{max}}\)

\(X = \frac{A_{n} - L_{opt}\cdot m_{L} - 2\cdot L_{opt}\cdot m_{X}}{m_{X}}\)

\(L = \frac{L_{opt}\cdot\left(m_{L} + 2\cdot m_{X}\right)}{m_{L}}\)

References

Trugman, A. T., Detto, M., Bartlett, M. K., Medvigy, D., Anderegg, W. R. L., Schwalm, C., … Pacala, S. W. (2018). Tree carbon allocation explains forest drought-kill and recovery patterns. Ecology Letters, 21(10), 1552–1560. http://doi.org/10.1111/ele.13136